Keyboards, being the input devices widely used in various electronic apparatuses, such as computers, cellular phones and PDAs, usually have their key caps being manufactured by plastic injection molding. However, after each key cap being injection molded, it usually required to be painted for providing the same with different appearances and colors as specified by customers. Recently, keys with scissors-shaped frames are vastly used in computer keyboard for such key has advantages, such as long stroke, good tactile sensation, low noise and long lifespan, etc. Nevertheless, for painting such keys with scissors-shaped frames, it is common to dispose key caps of such keys on a tool which is structured simulating a keyboard structure and is substantially a spray painting platform having a panel disposed thereon. As the panel is provide for scissors-shaped frames to be secured thereon while allowing the key caps to mount fixedly on the scissors-shaped frames, the key caps can be elevated by protruding columns formed on the platform for preparing the key caps for spray painting. After the spray painting, the whole platform with scissors-shaped frames mounted with key caps is to be processed by posterior processes, such as baking, printing, etc., and then the key caps are removed from the scissors-shaped frames. The most significant drawback of the aforesaid conventional spray painting tool is that: residue paint is going to adhere on the panel in each spraying and after several spraying, a stacking of residue paint is going to formed on the panel and thus the panel must be replaced, thereby, not only the cost is increased, but also as the replacing of such panel requires each and every scissors-shaped framed to be dismantled from the old panel and then to be installed on a new panel, a great amount of time is wasted and thus delaying the paint spraying process.